Refractometer and temperature

[jdpeters]

I’m sure the community is tired of basic refractometer questions but with a atc refractometer does the solution temperature need to match the aquarium temperature to be accurate?
When I pull my refractometer out of the closet and calibrate it, it generally need to be adjusted. It tends to read higher. When I put my tank sample on it after cleaning my tank reads lower than my solution.

Secondary question, would it make more sense to pull my sample out of the tank and let it get to the same room temp as the calibration solution?

 

[Nano_Man]

Most calibration fluids say 25c

 

[jdpeters]

The calibration fluid does say that but I’m confused if it matter if the refractometer claims to be ATC device.

Why would the calibration fluid have a specific target temp and why would it matter? Do I need to pull a sample of water out of the tank and let it match the temperature of the fluid first?

 

[hoffmeyerz]

My understanding is that ATC refractometers are calibrated with the solution and ambient temps at a specific range. After that the ATC system is supposed to correct for temp variations.
Personally I moved to the TM glass hydrometer and it was the best move I've made for checking salinity. I still have a refractometer and I keep it calibrated off the glass hydrometer to use for quick one-off checks.

 

[jdpeters]

My understanding is that ATC refractometers are calibrated with the solution and ambient temps at a specific range. After that the ATC system is supposed to correct for temp variations.
Personally I moved to the TM glass hydrometer and it was the best move I've made for checking salinity. I still have a refractometer and I keep it calibrated off the glass hydrometer to use for quick one-off checks.

I’m not understanding why the refractometer itself says 20c but the solution is for 25c.

I saw reef dudes suggest floating the solution in the tank for 5-10 minutes that way the solution matches the aquarium water.

I’ve been mixing my water on the concrete floor in my fish room and not heating the water for months but using the refractometer calibrated to 35ppt which sits in a ambient temp of around 78 which is much higher I assume than the cold ground. Wonder how much I’m complicating this and or throwing my salinity off

 

[hoffmeyerz]

My understanding is that ATC refractometers are calibrated with the solution and ambient temps at a specific range. After that the ATC system is supposed to correct for temp variations.
Personally I moved to the TM glass hydrometer and it was the best move I've made for checking salinity. I still have a refractometer and I keep it calibrated off the glass hydrometer to use for quick one-off checks.

I’m not understanding why the refractometer itself says 20c but the solution is for 25c.

I saw reef dudes suggest floating the solution in the tank for 5-10 minutes that way the solution matches the aquarium water.

I’ve been mixing my water on the concrete floor in my fish room and not heating the water for months but using the refractometer calibrated to 35ppt which sits in a ambient temp of around 78 which is much higher I assume than the cold ground. Wonder how much I’m complicating this and or throwing my salinity off

The refractometer has a strip of metal inside that slightly changes with a change in temp which pushes the scale and adjusts the reading based on the solutions temp. The refractometer needs to be calibrated at the proper temp to set the scale in the correct position so everything works right. Once calibrated at the right temp you don't need to adjust temp for readings unless you are recalibrating again.
A calibration solution is going to be mixed for a given salinity at a given temp.
Theoretically speaking if the refractometer is calibrated right and the scale is placed properly for the ATC then a third party calibration fluid should read right regardless of its temp.
All this is why I use the floating glass hydrometer now LOL!

 

[jdpeters]

The refractometer has a strip of metal inside that slightly changes with a change in temp which pushes the scale and adjusts the reading based on the solutions temp. The refractometer needs to be calibrated at the proper temp to set the scale in the correct position so everything works right. Once calibrated at the right temp you don't need to adjust temp for readings unless you are recalibrating again.
A calibration solution is going to be mixed for a given salinity at a given temp.
Theoretically speaking if the refractometer is calibrated right and the scale is placed properly for the ATC then a third party calibration fluid should read right regardless of its temp.
All this is why I use the floating glass hydrometer now LOL!

Are those new? I never really hear anyone use them. It seems like would be less user error?

 

[hoffmeyerz]

No, not new, there are a lot of people who use this. It's extremely accurate and easy to use never needing any calibration. It is made to read at a water temp of 77° but since I keep my tank at 78° the difference is too small to worry about. There is a temp correction table though if needed.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

 

[ReneReef]

…adjusts the reading based on the solutions temp.

Incorrect.

The sample takes on the temperature of the refractometer. The ATC corrects for changes in ambient temperature, NOT sample temperature.

 

[hoffmeyerz]

…adjusts the reading based on the solutions temp.

Incorrect.

The sample takes on the temperature of the refractometer. The ATC corrects for changes in ambient temperature, NOT sample temperature.

Sorry, I should have been more accurate. Technically speaking you need to leave the sample on the glass of the refractometer for a short period to adjust to the refractometers temp. And yes you are correct that the ATC will change the scale based on changes in ambient temp which the sample then adjusts to while sitting on the glass. I was speaking too simply.
Thanks for the correction!

 

[jdpeters]

No, not new, there are a lot of people who use this. It's extremely accurate and easy to use never needing any calibration. It is made to read at a water temp of 77° but since I keep my tank at 78° the difference is too small to worry about. There is a temp correction table though if needed.

High Precision Hydrometer

Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...

www.bulkreefsupply.com

Noted. I might get a new temp gun and try one out. I keep my tanks at 78 also

 

[painter1982]

I’ve wondered if temp matters. If you add a couple drops to the meter it would not take long for the water to be the temperature of the meter.